Switches in a PBX are typically characterized on a cost per line basis. The capacity of a switch is determined by the number of time slots in a frame which the switch is capable of handling. To provide both voice and data services in communications utilizing an existing PBX, two time slots were typically dedicated for voice and data transmission, respectively, so that the voice and data may be routed to two different destinations or receivers if desired. The disadvantage with this technique is that the number of possible subscribers which may be coupled to a PBX for voice and data service is reduced by one-half of the number of voice only subscribers. Further, the effective cost per line to provide data services with voice is therefore doubled. Auxillary switches may be added to an existing PBX to provide a data service and a voice/data service. However, additional control circuitry must also be added to control the auxillary switches and extensive modification of the existing conventional PBX design is typically required. Others have used a simultaneous voice and data transmission technique in a single time slot which does not reduce the line capacity of a PBX. However, both the voice and data must be routed to the same destination. In office environments such as a local area network, LAN, directing data and voice to separate locations such as to a telephone receiver and to a central word processor is typically required. Therefore, use of a single time slot which transmits both voice and data requires additional circuitry to implement a LAN with existing PBX equipment.